Abstract: Black rice has been paid more and more attention in recent years because of its high nutritional value, and its application value in food. Particle size is closely correlated with the physicochemical characteristics and processing characteristics of black rice flour, but the relationships have not been clarified. Therefore, to provide an important theoretical basis for the application of black rice flour, this study focuses on the starch characteristics of black rice flour with different particle sizes. Firstly, the black rice flour processed by a high-speed pulverizer is screened to obtain black rice flour with different particle sizes (< 0.15 mm, 0.15-0.18 mm, and < 0.18-0.25 mm) on this basis, the composition, hydration characteristics and gelatinization characteristics of black rice flour with different particle sizes were analyzed. With the decrease of particle size, the content of total starch and the ratio of amylose to amylopection in black rice flour decreased, while the content of protein and damaged starch increased. This result was attributed to the component distribution of the structure of black rice particles. Moreover, with the decrease of particle size, the water solubility index and swelling potential gradually increased. Meanwhile, the results of gelatinization characteristics showed that the peak viscosity, trough viscosity, final viscosity, pasting temperature and peak time all decreased with the decrease of black rice flour particle sizes. This may be due to the increased water absorption of fiber, which reduces the available water in starch gelatinization system. Moreover, the destruction of starch crystal structure facilitated water molecules to enter the particles through pore channels. After black rice starch was extracted by enzymatic method, thermal characteristics, crystal structure, short-range order and microstructure of the starch were further determined. The gelatinization enthalpy decreased with the decrease of the particle sizes of black rice flour, which may be related to the destruction of the crystal structure. The X-ray diffraction confirmed this assumption, showing a decrease in relative crystallinity. Essentially, continuous crushing resulted in the decrease of continuous crystallization area of starch, but did not change the crystal form of starch. Combined with the results of short-range order, it was speculated that the damage may mainly attributed to amylopectin branches and the intermolecular forces of whole crystal structure. Furthermore, scanning electron microscopy showed that the smaller the particle size, the rougher the surface of the starch and the more obvious the granule structure breakage. Overall, the change of starch granule structure and crystal structure induced the change of its physicochemical properties. Therefore, the influence of particle size on powder properties should be fully considered in the application of black rice flour to food.